Conventionally, some of measuring and controlling apparatuses for vehicles employ a method of radiating radio wave or light and measuring a distance to a target such as an automobile or obstacle ahead of the automobile and a relative speed with respect to the target.
As a radar apparatus utilizing radio wave, various kinds of millimeter wave radars are described in “Trend of Development of Millimeter Wave Radar for Vehicle”, The Journal of the institute of Electronics. Information and Communication Engineers, 1996, October, pp. 977-981, for example.
An example of radar apparatuses utilizing light is described in JP-A-8-261753.
Further, such a technique is proposed that a camera is mounted on a vehicle, then the camera photographs or picks up an image of a vehicle ahead, and the image thus image picked-up or photographed is subjected to an image recognition processing thereby to recognize the vehicle ahead.
A method in which a vehicle trying to cut in is detected in advance by using both the radar apparatus utilizing light or radio wave and the image processing apparatus utilizing a camera is described in JP-A-11-321379. A method of improving recognition efficiency of a vehicle ahead is described in JP-A-6-231398 etc.
JP-A-10-160835 describes a technique in which a camera and a scanning type laser radar are used in a manner that a beam of the laser radar is scanned in synchronism with the synchronizing signal of the camera, whereby even if plural vehicles ahead are photographed in an overlapped manner, distances to subjects within an image photographed by the camera are grasped on a pixel unit basis and an overlapped state of the plural vehicles ahead are recognized.